they both use oil
it takes up space
if your rider mower uses petrol/gasoline then you can remove the spark plug after you have tried to start it and if there is fuel getting to the engine the plug will be wet with fuel,if however it is dry then no fuel is present.
It maters what type it is but is properly the fuel line
The fuel filter for a Honda self propelled push mower with a Briggs and Stratton engine is located between the fuel tank and the carburetor. The fuel filter is only about one inch long.
Just make sure the engine is not running and pour in the fuel. If the engine is hot let it cool before refueling.
Probably that it's a carburetted and not a fuel injected engine.
There is not really a set fuel air mixture. Each engine will be different even if they are the same engine during the build process they are set specifically to the engine.
For small motor bike or lawn-mower or similar.
You probably have a dirty carburetor causing that surge.
The choke on a lawn mower engine carburetor is used to ease starting when the engine is cold. It closes a valve inside the carb, restricting airflow, but keeps the throttle open so fuel is unrestricted. This excess of fuel (rich mixture) increases the volatility of the cylinder charge.
If you put it in for engine oil you will have a major problem. If you put it in with the fuel then you will notice the mower smoking a lot and possibly fouling the spark plug.
if it is a 2-stroke engine then it only can be 1 of 3 things, the spark, the fuel or the compression.